A number of different methods have been proposed to effect a compressive force on fibrous thread interlaced web material in order to impart pre-shrinkage properties to the material. One such method and apparatus is disclosed in U.S. Pat. No. 4,447,938 wherein a fibrous web material is forced into a stuffing chamber where the stuffing chamber is formed by a confining means having an apex like extension and two movable surfaces with the apex or extension extending in part between the surfaces.
A passageway is formed between one side of the extension and one movable surface and the passageway continues between the other movable surface and the other side of the apex.
The fibrous web material is disposed to run through the passageway as it is compacted. The two movable surfaces may be positioned close to each other to decrease the size of the passageway and stuffing chamber so that the material forced into the chamber is caused to contact and turn on the apex of the confining means. This results in a kneading or working action being imparted to the fibers or yarns forming the material which assists in the repositioning of the fibers while the material is in a compressed state.
Where even a greater reduction of shrinkage potential is desired an impact blade may be positioned between the first and second movable surfaces to extend into the stuffing chamber to prevent movement of the web material into the space between the movable surfaces caused by compressive forces exerted on the fabric material.
When the two surfaces are positioned further apart to enlarge the passageways and stuffing chamber, the material in the stuffing chamber will be slightly spaced from the apex such that both sides of the web material will be spaced from the wails of the stuffing chamber a slight amount. This allows easy repositioning of stitches when the material is subjected to a heat or steam treatment in order to puff or swell the individual yarns.
If an approach could be developed to treat web materials that were slit open and then presented to the unit in a single layer benefits in operation would be forthcoming to the manufacturer - also the machine could be used to compact a wider variety of web materials.
However when larger diameter movable surfaces were used to assure roll straightness this did not permit the formation of passageways having an optimum configuration to achieve maximum compaction and constant fabric material treatment.
Also at times when these larger rolls were used there developed difficulty in the movement of the fabric material through the passageways particularly if there were slight variations in fabric thickness or uniformity. Use of smaller rolls as movable surfaces were more forgiving but at times deflection of the rolls occurred to change the dimensions of the passageways which interfered with material compaction. This deflection was most pronounced when the face of the roll is greater then about 10 times the roll diameter. It will be clear that use of smaller sized rolls will enable a producer to manufacture a machine that is less expensive to build and easier to maintain. However due to the roll deflection larger rolls were required with concomitant alteration in passageway size along with changes in the size of the stuffing box.
It will be understood that the invention contemplated herein will function equally well on an arrangement wherein the fabric flows into the chamber formed by a confining means and a first movable surface and from where the fabric moves down and around the apex of the confining means and then upwardly on the other side of the apex or extension and around the other movable surface. The concept will also work as well on a similar arrangement where the fabric is moved through the stuffing chamber and downwardly around the second movable surface. The invention disclosed herein permits use of the smaller rolls and allows the user to obtain the resultant benefits.
It is therefore an object of my invention to provide an apparatus which is useful to shrink fibrous web materials in a more efficient manner and accomplish this pre-shrinking on a machine that is less expensive to manufacture and easier to maintain.
It is a further object of my invention to provide for an apparatus that is more versatile so that a large variety of fibrous webs may be compressively shrunk to more demanding conditions.